A recent development in the field of flash photography has been the packaged linear flashlamp array. Developed for use with a highly automated camera, this flashlamp packaging arrangement is formed of two operational faces, each exhibiting an array of five flashlamps. Accordingly, when utilized in conjunction with an automatic camera, a rapid succession of photographic cycles may be carried out inasmuch as no mechanical indexing or aligning of flashlamps need be performed following each exposure.
Described in detail in U.S. Pat. Nos. 3,598,984 and 3,598,985, the dual arrays of flashlamps are compactly packaged by internesting the oppositely disposed flashlamps of each face thereof. The igniting terminals of individual lamps within the packaged arrays are connected by printed circuit technique to a downwardly extending blade mount, each side of which is configured to expose five input contacts, a common bus or lead and a circuit completing conductive surface. By inserting the downwardly extending blade mount within an appropriate receptacle within the noted camera, electrical connection is made with the five input contacts of an operationally facing array and the noted conductive surface serves to provide circuit completing contact for switching the control system of the camera into an operational mode suited for flash illumination. This operational mode as well as the general features of the automatic camera are described in detail in a copending application for U.S. patent by J. P. Burgarella et al., Ser. No. 333,331, filed Feb. 16, 1973, and assigned in common herewith now issued in U.S. Pat. No. 3,820,128.
To ignite successive ones of those flashlamps within an appropriately oriented operational face of an array, flash firing circuits are incorporated within the camera. Typical of such circuits is that described in U.S. Pat. No. 3,676,045. These circuits generally incorporate discrete firing networks which operate in conjunction with an aligning circuit to sequentially ignite an individual flashlamp with each actuation of the camera. The aligning circuit operates in accordance with the terminal or output characteristics common to the design of the flashlamp.
The general structure of a flashlamp with which logic sequencing or firing circuits must operate includes a glass envelope within which is sealed a quantity of combustive filamentary strand material or the like and a combustion supporting gas. This combustable component of a lamp is positioned in intimate relationship with the filament of an igniting assembly electrically coupled across the input leads of the lamp. Upon application of current to the terminals of the flashlamp, the igniting filament rapidly heats to the combustion point of the strand material and flash ignition ensues. Following ignition, the igniting filament as well as the strand material is melted and/or reduced to an ash residue which remains within the glass envelope. As a result, the terminals leading to a glass envelope are open circuited and the switching circuit to which they are coupled witnesses an infinite resistance. Should the igniting filament or strand of material incompletely combust and short the otherwise open circuited terminals of a flashlamp, a relatively high resistance will be witnessed across the terminals. The flash firing circuits react to a predetermined ohmic value across the fired or unfired bulb to derive the noted sequential selection of lamps for ignition during a given photographic cycle.
Following the expenditure or ignition of five flashlamps within one operational face of a packaged array, the operator removes the packaged array and reinserts it within the camera mounting structure in reverse to present the oppositely disposed operational face, thereby accommodating for a next five photographic flash cycles.
Often taken with the excitement of the "photographic moment" of a scene, a photographer may fail to perceive that all flashlamps within the operating side of an array have been ignited.
Failure to reverse or replace the array will cause an ensuing photograph to be aborted for improper illumination.